The present invention relates to an improved structure of a golf club head, and more particularly to a golf club head which can transfer the percussion force from the hitting point quickly and evenly to the other portions of the golf club head to absorb the vibration when the golf club head hits a golf ball. Therefore, the golfer can more easily control the flying direction of the golf ball.
Conventionally, a golf club head is made of wood of a high degree of hardness, or metal. The wooden club head is easily affected by moisture and therefore it needs complicated maintenance. The metallic club head must be made a small size due to its weight because of the physical property of the material. Although the wooden club head has a better toughness and resilience, its degree of hardness is less. Moreover, if its grain is not oriented well, the club neck will be subjected to large torque and shear forces under the instaneous percussion force of thousands of kilograms when the club hits the ball. This causes deviation of the flying direction of the ball, and even causes the club to be broken. Although the metallic club has a better hardness, it is brittle, easily split, and has less toughness and resilience. When the metallic club head hits the ball, the vibration cannot be absorbed well, and will transfer to the arm of the golfer. This makes the golfer uncomfortable and affects the control of the flying direction of the golf ball.
For solving the above drawbacks, composite materials, such as carbon fiber, have been recently been utilized to improve the structure of the club head. For example, a reinforced layer of composite material interposed between each two adjacent thin wood plates to increase its strength has been developed. However, the surfaces of the wood plates must be provided with a plurality of teeth and grooves to firmly engage with the composite material. Such a structure is difficult to be practiced, since if the numbers of the teeth and grooves are too little, the securing is not firm, while if the numbers are too many, the wood fiber will be destroyed, resulting in less strength.
Furthermore, a club head made of carbon fiber mixed with acrylnitrile butadiene styrene (ABS) by an injection molding process has been developed, as shown in FIG. 1. Its material is selected chopped fiber to prevent the fiber from blocking the nozzle of the injection molding machine. However, such a material has less strength, therefore, a reinforced hitting plate 11 made of long fiber or resin by a compression molding process is secured to the hitting surface, resulting in an increase in cost. In addition, it is necessary that gaps are not allowed to exist between the club head and the reinforced hitting plate 11, since, if so, the stress concentration phenomenon, which frequently causes the hitting plate 11 to be broken, will occur. Moreover, for saving the amount of used material and for faciliating the removal of the die, the club head includes a chamber 12 having an opening at the bottom of the club head, and a protecting plate 13 secured to the bottom and covering the opening. Obviously, the transfer of the action force is terminated at the opening of the chamber 12, whereby the force cannot be transferred to the other portions of the club head quickly. Therefore, vibration cannot be absorbed adequately, and the flying direction of the ball cannot be controlled properly.